22 million businesses and education customers are actually using Windows 10, the company says. It's not clear how many of those are businesses and how many of them are schools, but in November, Microsoft said that 14 million Windows 10 devices were up and running on enterprise computers.

Most analysts expected businesses to get serious about upgrading their employees to Windows 10 in 2016, and if 76% of them are in pilots, that's certainly a sign that things are on track.

Why Windows at work matters for Microsoft

Getting businesses to run Windows 10 is important to Microsoft for all sorts of reasons.

Unlike consumers who were offered a free upgrade (pestered might be a better word), businesses aren't completely off the hook when it comes to paying for Windows. Most of them can upgrade to Windows 10 for "free" because they've already bought enterprise contracts that allow them to use any supported version of Windows. But they do have to pay Microsoft periodic license fees for every PC running Windows so they can keep running the most up-to-date and advanced business version.

Plus, when businesses are using the latest version of the PC operating system, that encourages them to upgrade all their other Microsoft business software to current versions, whether that's Office 365, Windows Server, or Microsoft's SQL Server database, and those upgrades will usually incur additional fees.

It's true that Microsoft is slowly weaning itself from its Windows empire, and encouraging businesses to rent all of their Microsoft business software from Microsoft's cloud, whether that's Microsoft Office 365, SQL Server, or Microsoft Dynamics (its competitor to Salesforce).

When businesses use its cloud, Microsoft makes money even if a company's employees don't use Windows PCs.

But Microsoft makes far more money if it can keep its business customers in its Windows ecosystem. And that really does begin with the PC.